Grip bolt



Oct. 14,1947. E. J. COLE 2,428,783

' GRIP BOLT Filed April 13, 1944 v v 2 sheets-sheet 1' Patented Oct. 14, 1947 GRIP BOLT Edward J. Cole, Peekskill, N. 'Y.

Application April 13, 1944, Serial No. 530,807

7 Claims.

This invention relates to a standard grip bolt and to a method of preparing such a bolt, and more especially to a grip bolt or cap screw which may be readily fabricated from a standard threaded bolt of any size or description or from a previously prepared blank before threading.

An object of the invention is the processing, by a series of simple'steps, a standard threaded bolt in such a manner that wnen a conventional threaded nut or other threaded part is threaded thereon the nut or other threaded part will be gripped or held without distorting or destroying the threads thereof, while'maintaining the nut or other threaded part' onthe bolt in a firm through removable position.

A further object is to modify a standard bolt or cap screw in such a manner that when coupled with a conventional threaded nut the modified thread of the bolt or cap screw will take up all play or tolerance and create a pressure between the threads of the bolt and cooperating nut or other threaded part. Thus the parts are maintained in tight frictional control without the use of jamb nuts, lock washers or the like and the threaded members will not work loose when subjected to shock and vibration.

Heretofore many proposals have been made to accomplish this object, but all of the prior suggestions have necessitated the formation of special bolts with special threads, which are costly to manufacture or result in destroying of the thread of the 'bolt and/or nut. By following the teachings of this invention a standard bolt or cap screw is produced which will have considerable binding and elastic retention grip action on the threads of a standard nut or other threaded part and in so doing will prevent the nut or other threaded part from working loose.

In the drawings:

Fig. 1 is an illustration of a standard SAE bolt, and it is intended to represent any conventional type of bolt or cap screw;

Fig. 2 illustrates the standard threaded bolt, partly in cross-section, initially processed by forming a groove or a plurality of equi-spaced grooves therein which are V-shaped in cross-section and arcuate in formation along the bottoms of the slots;

Fig. 3 shows a standard bolt after it has been slotted and one of its slots flared or spread;

Fig. 4 is a cross-section through the initially processed bolt taken on line 4-4 of Fig. 2;

Fig. 5 is an enlarged fragmental sectional view showing the formation of the curved V-s'haped groove in association with a standard thread formed on the threaded portion of the bolt;

Fig. 6 is an enlarged sectional view illustrating the manner of spreading or flaring the central, portion of each of the V-shaped grooves by means of an arcuate faced tool; and

Fig. '7 is an enlarged sectional view illustrating the form of the spreading tool per se shown in Fig. 6 and the manner in which the tool contacts a portion of the V-shaped groove'beginning at or near the root of the thread and displaces the metal of the thread'on either side of the groove. Specifically, in the drawings numeral l denotes a conventional standard bolt which in the'form shown has the customary shank 3, outer threaded end '5, and integral wrench engaging head" 1. Such a standard bolt is cut or slit to provide one or more longitudinally extending slots 9 therein. These slots preferably extend from the beginning of the thread 5 through any desired portion of the threaded part of the shank 3, and as shown in Figs. 2 and i the slots 9 are V-shaped in crosssection and have an arcuate or curved bottom wall line. It is desirable to cut or slot the V-fshaped groove or grooves 9 into the threaded portion of the'bolt so that the arcuate bottom wall II thereof is flat, or' can berounded if desired, as illustrated in enlarged view 5 It will be ob vious to those skilled in'the art thatthe' series of longitudinal, arcuate V-shaped slots 9 maybe ground, pressed or cut into the bolt simultaneously by any suitable type of machinery.

After the plurality of V -shaped slots 9 have been formed in the bolt it is thereafter proces'sed to form the thread or retention grip in the manner disclosed in Figs. 6 and 7.

Fig. 6 shows a manual or automatically projected flaring tool l5 after it has been inserted into one of the V-shaped grooves 9. It will be observed that the forward end or working face I! of the tool I5 is arcuate and of the same radius as the curved bottom ll of the V-shaped groove 9, although of lesser width than the length of the groove.

Referring now to Fig. '7, it will be observed that the thickness of the tool [5 is such that when inserted in the V-shaped groove II it will contact the side converging walls of the groove 9 at a point approximately at the root of the bolt thread 9. This first point of contact by tool [5 is indicated by the numeral l9. The tool is then forced into the groove 9 for a substantial distance below the point I!) but not to the bottom of the groove. During this forcing or flaring movement the rounded end 2| of the tool l5 laterally displaces the metal of the thread 5 immediately adjacent the side walls of the groove 9. This displacement and flow of metal is indicated by the numeral 23 and the dotted lines in Fig. 7. As before stated the flaring tool l5 is not forced to the bottom of the groove 9 and consequently the tool does not strike the arcuate bottom wall I l thereon and its movement is only sufficient to flare or bulge the thread 5 throughout the width of the tool I5. The resulting form is shown in Fig, 8. All of the slots 9 are thus similarly treated and the re- 3 suit is a standard bolt having a plurality of slightly flared or bulged portions spaced around its periphery.

In use a nut or threaded member can be readily turned on to the outermost portion of the bolt and as soon as the thread of the nut comes into contact with the bulged or flared portions 23 of the bolt the play or looseness is taken up and the flared portions 23 of the bolt bind against the threads of the bore. A tight grip is thus produced which defeats accidental removal of the nut, as by vibration, shock, etc., but does not prevent the nut to be removed therefrom by means of a" wrench. The nut may be applied and taken on of a bolt formed according to this invention many times without destroying the efiectiveness of the grip and without harming the thread of the operating threaded member.

I claim: 7,

1. A grip bolt for use with a standard threaded member, said bolt having a conventionally threaded shank, one or more longitudinally extending slots of arcuate form and V-cross-section spaced around the threaded portion of the shank, the thread on said boltbeing flared adjacent each side of said slots beyond the normal diameter of the'remainder of the thread.

2. A frictional grip bolt for use with a conventionally threaded member comprising a threaded shank, a series of longitudinal slots extending through a portion only of the threaded section of the shank, the said slots having outwardly flared portions adjacent the side edges of the slots and extending slightly beyond the periphery of the unflared portions of the shank thread. i

3. A grip bolt for use With a conventionally threaded member comprising a standard threaded shank having a plurality of longitudinally extending slots formed in the threaded portion thereof, each of said slots being V-shaped in crosssection' and of arcuate form, the metal immediately adjacent the midsection of the side walls of the V-shaped sloped slots being flared whereby the adjacent shank thread is of larger diameter than the remainder of the thread.

4 wherein the threaded portion of the bolt has a series of straight, parallel, spaced apart slots cut therein for less than the length of the threaded,

the said series of slots are equi-spaced around the periphery of the thread portion of the bolt and the flared areas are separated by areas of normal thread.

6. A grip bolt as defined in claim 4 wherein the said slots are generally V-shaped in crossr 4. A threaded grip bolt adapted to frictionally bind the thread of a cooperating nut or the like flared in their central portions and gradually taper toward each end.

. EDWARD J COLE.

REFERENCES cI'rED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,495,687 Grosclaude May 27, 1924' 1,761,581 Northey et a1 June 3, 1930 2,251,201 Purtell July 29, 1941 1,059,260 Barrett Apr, 15, 1913. 1,210,310 Hickling et al Dec. 26, 1916 909,033 Smith Jan. 5, 1909 1,158,454 De Camp Nov. 2, 1915- 33,487 Marsh Oct. 15, 1861 1,874,657 Trotter Aug. 30,1932 1,363,710 Best Dec. 28, 1920 2,266,758 1 Holtz Dec. 23, 1941" 2,251,201 Purtell July 29, 1941 949,741 Loehr Feb. 15, 1910 2,232,336 Meersteiner Feb. 18, 1941 2,302,675. Cherry; Nov. 24, 1942 1,235,626 Woodward Aug. 7, 1 917 FOREIGN PATENTS Number Country Date 1 Switzerland Sept 17, 1928; 

